Pregnant women who gain weight rapidly during the early stages of pregnancy are at higher risk for gestational diabetes, a new study found.

Action Points

Explain to interested patients that rapid weight gain during early pregnancy is associated with increased risk of gestational diabetes.

Note that diabetes risk was most strongly associated wth rapid weight gain during the first trimester.

Pregnant women who gain weight rapidly during the early stages of pregnancy are at higher risk for gestational diabetes, a new study found.

Compared with pregnant women who gained weight at the slowest rate (less than 0.60 pounds per week), the fastest weight gainers (more than 0.89 lb/week) were 74% more likely to develop gestational diabetes mellitus (OR 1.74, 95% CI 1.16 to 2.60), according to an online report published Feb. 22 in Obstetrics and Gynecology.

Women who gained from 0.60 to 0.88 lb/week (the middle third of weight gainers) were at 43% higher risk of developing gestational diabetes than the lowest weight gainers (OR 1.43, 95% CI 0.96 to 2.14).

The link between weight gain and diabetes risk was primarily attributable to putting on pounds during the first trimester of pregnancy.

"Our study is one of the first to support a direct association between gestational weight gain and the risk of [gestational diabetes]," Monique Hedderson, PhD, of Kaiser Permanente Medical Group in California, and colleagues wrote.

"These findings need to be replicated in other racial/ethnically diverse populations. Clinicians should be aware that high rates of weight gain during early pregnancy may increase a woman's risk of [gestational diabetes], particularly among overweight or obese women."

Gestational diabetes, defined as glucose intolerance with onset or first recognition during the second or third trimester of pregnancy, affects 4% to 7% of pregnancies in the U.S.

The disease is associated with increased risk of perinatal complications, and women with a history of gestational diabetes and their children are at high risk of developing type 2 diabetes mellitus. Few studies, however, have explored the relationship between between gestational weight gain and the risk of gestational diabetes.

Hedderson and colleagues conducted a nested case–control study of a multiethnic group of pregnant women, of whom 345 developed gestational diabetes and 800 served as controls. The participants all lived in Northern California and delivered between 1996 and 1998.

They were screened for gestational diabetes at 24 to 28 weeks of gestation, and their plasma glucose levels, weight, and other data were obtained by a review of their medical records.

The researchers noted that they relied on self-reporting to determine the women's weight prior to pregnancy, which could have been unreliable. They were also missing medical chart records of weight for about 15% of women and lacked information on diet, physical activity, and other factors that might have had an influence on whether or not a woman developed diabetes.

The researchers theorized that rapid weight gain in early pregnancy may result in an early increase in insulin resistance that leads to the "exhaustion" of the B cells. This, in turn, could reduce the capacity of the B cells to secrete adequate levels of insulin to compensate for the insulin resistance induced by the progression of pregnancy.

"Although we were unable to measure the components of gestational weight gain (e.g., maternal fat mass, fat-free mass, mass of the fetus), weight gain in early pregnancy has been found to consist of more maternal body fat," they wrote.

"Large gains in maternal fat mass in early pregnancy could have a stronger influence on subsequent insulin resistance and, consequently, [gestational diabetes] risk than later gains in lean tissue or fetal mass."

They concluded that "avoidance of excessive weight gain early in pregnancy may be an effective strategy for prevention of GDM, but randomized studies are needed to determine the feasibility of such an early intervention and the best methods to help women meet the IOM recommendations for gestational weight gain."

The study was funded by the National Institute of Diabetes and the American Diabetes Association.

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